This invention relates generally to vehicle tire pressure control systems, and more particularly relates to a system for transmitting power to an aircraft tire pressure sensor from a control unit associated with a wheel hub and transmitting data between the aircraft tire pressure sensor and the control unit. The invention pertains more specifically to a communication link between a tire pressure sensor on a wheel rim and control electronics connected to a wheel hub, particularly for aircraft.
It is useful in an airplane to measure the pressure of each tire and display this information in the cockpit. It is necessary to communicate this information from the wheel rim to the hub, from the wheel hub to the electronics located on the wheel axle, and then from the electronics unit to the cockpit.
One known tire pressure system uses a pair of transformer coils to communicate between a primary and secondary coil in the wheel axle. These transformers are coaxial and face each other. A length of wire connected to the secondary of the transformer pair connects directly with the tire pressure sensor that is located on the periphery of the wheel rim. Another known device for enhancing the magnetic coupling in a RFID wireless communication system includes first and second antenna coils connected together by electrical connectors in a closed loop and formed on a flexible substrate that can be folded around a magnetic flux blocker to avoid magnetic interference from the magnetic flux blocker. However, it is desirable to provide communication between an airplane wheel hub and a tire pressure sensor located on the rim of the wheel up to six inches away from the wheel hub without using electrical connections that can be unreliable and easily be broken in a harsh airplane wheel environment. It is thus desirable to provide a non-contact method of communication between an airplane wheel hub and a tire pressure sensor located on the rim of the wheel that does not require electrical connections or a length of wire to communicate between the wheel hub and the tire pressure sensor.
A magnetically coupled antenna range extender is also known that is structured to be interposed between an RF antenna and an electronic device from 0.5 to 5 centimeters from the RF antenna or the electronic device, for extending the operating range of communication between the RF antenna and the electronic device. The antenna range extender includes a passive series tuned resonate circuit that must be tuned to resonate substantially at the frequency of an RF signal radiated by the RF antenna. The passive series tuned resonate circuit can be formed by an open loop coil of an electrical conductor, with a capacitor connected in series and completing the circuit. However, it has been found that an electromotive force can be induced in such a loop by stray magnetic flux that can generate an electric current that can interfere with a desired signal being conducted.
A need therefore remains to reduce the cost of the device that links the two coils, and to reduce the complexity of the device that links the magnetic field, in a manner that avoids the generation of signal interference, the use of unreliable electrical connections, and the use wires for electrical connections, which can easily break in the harsh environment of the airplane wheel. The present invention fills this and other needs.